Add an UNSPEC_PROLOGUE_USE to prevent the link register from being considered dead.

Add a testcase for the bug fixed by this patch.

From-SVN: r61509

gcc/ChangeLog

+2003-01-20  Nick Clifton  <nickc@redhat.com>
+
+	* config/arm/arm.md (sibcall_epilogue): Add an
+	UNSPEC_PROLOGUE_USE to prevent the link register from being
+	considered dead.
+
 Mon Jan 20 14:36:23 CET 2003  Jan Hubicka  <jh@suse.cz>
 
 	* i386.md (SSE cmov splitter):  Handle memory operand in operand 5.

gcc/config/arm/arm.md

@@ -8430,8 +8430,14 @@
   "
 )
 
+;; Note - although unspec_volatile's USE all hard registers,
+;; USEs are ignored after relaod has completed.  Thus we need
+;; to add an unspec of the link register to ensure that flow
+;; does not think that it is unused by the sibcall branch that
+;; will replace the standard function epilogue.
 (define_insn "sibcall_epilogue"
-  [(unspec_volatile [(const_int 0)] VUNSPEC_EPILOGUE)]
+  [(parallel [(unspec:SI [(reg:SI LR_REGNUM)] UNSPEC_PROLOGUE_USE)
+              (unspec_volatile [(return)] VUNSPEC_EPILOGUE)])]
   "TARGET_ARM"
   "*
   if (USE_RETURN_INSN (FALSE))

gcc/testsuite/ChangeLog

+2003-01-20  Nick Clifton  <nickc@redhat.com>
+
+	* gcc.c-torture/execute/20030117-1.c: New test case.  Exposes
+	problem with ARM sibcall code generation.
+
 2003-01-20  Kazu Hirata  <kazu@cs.umass.edu>
 
 	* gcc.c-torture/execute/20030120-1.c: New.

gcc/testsuite/gcc.c-torture/execute/20030117-1.c

+int foo (int, int, int);
+int bar (int, int, int);
+
+int main (void)
+{
+  if (foo (5, 10, 21) != 12)
+    abort ();
+
+  if (bar (9, 12, 15) != 150)
+    abort ();
+
+  exit (0);
+}
+
+int foo (int x, int y, int z)
+{
+  return (x + y + z) / 3;
+}
+
+int bar (int x, int y, int z)
+{
+  return foo (x * x, y * y, z * z);
+}